Check out American Radiological Nurses Association. They offer a Core Curriculum (4 yr ago it was $75), and you can obtain a CRN certificate from them. (was $250 to test, last I knew)
They also sponsor yearly meetings along with what used to be SCVIR (Society for Cardiovascular and Interventional Radiology), and what is now SIR (Society of Interventional Radiology, I believe). It may even have changed names in the last 3 yr or so . . .
You could always get yearly refresher courses on Moderate Sedation . .. and Stress Testing . . do a google or yahoo or vivisimo search.
There didn't used to be more than that one yearly meeting for Rad. Nurses, which was REALLY too bad, given all that position could entail.
There are several very good Interventional Radiology books written for the tech and nurse, check on Amazon
Good luck carving out that very important niche!!